Aircraft assembly includes joining of complex, large-scale components in precise relationships, often necessary to efficiently transfer forces between such components. For example, wings and portions of the empennage (e.g., vertical stabilizer, horizontal stabilizer) may be pre-assembled and then after-attached to corresponding sections of the fuselage using load-bearing joints.
To achieve the appropriate fit between mating aircraft components, shims (also called fillers) are often used when joining parts together. Shims are used to occupy gaps (or voids) between joined parts. In many cases, such gaps or voids are specifically designed into the structure, as an example, to facilitate positioning and alignment of components during assembly. The use of shims to fill gaps during assembly improves fit between mating components.
In many cases, gaps are modelled with relatively uniform dimensions. However, in other situations, measurements across and along the gap may be non-uniform. In such cases, shims are typically custom-sized to fill the gap precisely and/or require special installation procedures. Measuring non-uniform gaps, preparing appropriate shims, and properly installing such shims is a time-consuming and tedious process that increases manufacturing cycle time.